Caroline Lucas giving a keynote speech, with Rupert Read looking on, at the autumn conference of the Green Party of England and Wales, Hove, 2006

Read was one of 13 Green Party councillors in Norwich, where he was first elected in 2004 to represent Wensum ward [6] and re-elected in 2007 with 49% of the vote.[7] He sat on the Joint Highways Committee of the city and county councils,[8] and was spokesperson on Transport for the Green Party city councillors.[9] Read stepped down from local politics in 2011 and Wensum was retained by the Green Party.[10]

Having held a number of officer posts for the Eastern Region Green Party, at the beginning of 2007 Rupert Read was selected as Eastern Region Green Party's lead candidate for the European Parliament elections in 2009 and again in 2014.[11] The East of England is one the Green Party's stronger regions in terms of support, and under the proportional representation system on which the European Elections operate, the Party was optimistic that he would represent them in the European Parliament. However, he was beaten to the last of the seven seats in the constituency by the United Kingdom Independence Party (UKIP) in 2009, and similarly in 2014. He stood in the Norwich North by-election, 2009, as the Green Party candidate, and returned the biggest by-election vote share in Green History with 9.7% of the vote.

Read stood as MP candidate for Cambridge in the 2015 general election.[12] He came fourth, having received 8% of the vote.[13]

Read was a regular contributor to the One World Column in the EDP, focussing on international development, poverty, globalisation, peacemaking, human rights, international relations and the environment.[14]

Rupert Read has developed, on the basis of his research in political and environmental philosophy, a radical proposal for institutional reform, to provide a place in the UK's democratic system for a voice for future people.[16] The proposal was launched at Parliament on 10 Jan 2012.

In January 2015, Read apologised for tweets in which he was interpreted as describing trans women as "a sort of 'opt-in' version of what it is to be a woman",[17] though he denied he did or ever had believed this and further stated: "I do not and never have believed that trans-women are not real women, or are any less women." He said he did not consider being a trans woman a choice.[18] He said he did not stand by everything he had written two years earlier and did not consider being a trans woman a choice. His comments caused concern within the LGBTIQ Greens, who invited him to "engage with LGBTIQ Greens and listen to our deep concerns over his comments on trans people and of the phenomena that is trans."

Read took up this offer and spent time with trans people in an effort to fully understand their lives. In his subsequent apology, Read said that "most of the offence caused by my tweets is a result of misunderstandings generated by the fragmented and angry nature of so much debate on Twitter" and reiterated that "it is up to women, not anyone else – and certainly not me – to decide who gets let into women-only spaces ... All women have a right to be involved in making those decisions." He also said he "reject[s] transphobia completely". In a separate article he stated[19] Read made a further apology in the Independent in which he said: that "trans people ... need our active engagement in the issues they face" and referred to some of the difficulties trans people face and his meetings with trans Greens.[20]Peter Tatchell and Mary Beard were among the signatories to a letter to the Observer which criticised the "censorship and silence of individuals", and explicitly mentioned Read.[21]Tatchell says he received thousands of critical comments in response to this, some of which were hateful or threatening.[22]